The construction of the Ada System Dependency Analyzer (SDA), a software architecture analysis tool that can process thousands of Ada source files during a single run and report on them as a group of files composing a single Ada system, is described. Such a tool is useful in software maintenance and in porting software from one environment to another. The authors not only give a good introduction to the SDA in this paper, they point out its extensibility and portability. The software development methodology employed for this tool was a modified spiral model [1] methodology. Two key technologies have been deployed in the construction of the SDA tool: compiler construction via parser generator, and object-oriented analysis, design, and implementation. This paper shows the role of the Aflex and Ayacc tools obtained from the Acardia project at the University of California at Irvine in the Ada SDA. The paper also explains the role of executive objects in the Ada SDA. The paper goes on to explain how the SDA identifies Ada source code dependencies on commercial off-the-shelf software products, specific Ada compilers, operating systems, and non-Ada routines. Identification of such dependencies is helpful in determining the part of the code that is likely to be a problem in porting the Ada system being investigated. The SDA tool’s reporting formats are also explained in the paper. The paper fulfills its purpose of introducing the SDA tool to the reader. I thoroughly enjoyed this paper.